1. Field of the Invention
The invention relates to an in-wheel motor and a wheel assembly with this in-wheel motor.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-2005-73364, for example, describes a related wheel assembly with an in-wheel motor, which includes a motor, a rotating shaft that rotates according to output torque of the motor, an oil pump provided at one end of the rotating shaft, and an oil passage that supplies oil from the oil pump to an outer periphery of a stator core of the motor. In this wheel assembly with an in-wheel motor, the oil from the oil pump is supplied into the motor from the outer periphery of the stator core of the motor via an oil passage which has an open end at the upper portion of the motor case. The oil supplied in this way is used to cool the stator core and the stator coil, after which it is used to lubricate the bearings that support the shafts of the motor and a reduction gear.
However, in the related art described above, the processing to form the oil passage, which has the open end in the upper portion of the motor case, in the motor case is difficult. That is, in the foregoing related art, the oil passage is formed by drilling a hole in the motor axial direction in the peripheral wall of the motor case, and then forming another passage that connects to the terminal end of that hole by drilling another hole from the inner peripheral side of the motor case toward the outside in the radial direction. This processing is not easy and requires many machining hours.